They do upgrade some cars port side for things like wheels and body kits so that bit may be true, but how can they lose it? Doubt if you will get anywhere tomorrow as it's Saturday and I don't think Lexus UK will be open.

Well I agreed to purchase a used Lexus ( about a year old ) a number of years ago. Put a deposit on the car over the phone based on description and pictures. Turned up to pay but inspected car first, massive deep scratch on bonnet, plus smaller scratches. Scuffed wheels. Salesman tried to blame it on a cat.
Needless to say I walked away and eventually got my deposit returned.
This was about 10 years ago so dealership hopefully would have improved, but I would never go back.